Optical writing device, optical reading device, recording-medium writing method, including wobble signal evaluation features

ABSTRACT

When performing writing and/or reading of information to/from an optical disk provided with a wobble including time axis information, an occurrence of a reading error of the time axis information from the wobble is suppressed so that disabled reading of information from the optical disk and an occurrence of a writing error can be prevented. Evaluated parameters such as a CRC error rate of an ATIP signal, an FMDT jitter amount and a phase error between an ATIP synchronization signal and a frame synchronization signal of writing data are evaluated based on a range of set values. When the evaluated parameter is deviated from the range of set values, writing and reading speeds are changed, thereby increasing the reading accuracy of the wobble signal.

TECHNICAL FIELD

The present invention relates to a device for performing writing and/orreading of information to/from an optical recording medium such as anoptical disk and an optical card. More specifically, it relates to anoptical writing device, a recording-medium-writing method, an opticalreading device, and a recording-medium-reading method, which use anoptical recording medium provided with a wobble including addressinformation.

BACKGROUND ART

As an optical disk permitting writing of information, there are a CD-R(CD-Recordable) and a CD-RW (CD-Rewritable) for a CD standard, and aDVD-R, a DVD-RW, a DVD+R, a DVD+RW and a DVD-RAM for a DVD standard. Forexample, a groove is cut in a CD-RW disk substrate with a sine waveshape or the like. The part of a recording layer corresponding to thegroove is a recording track. The serpentine of the groove is called as awobble. To the wobble, FM-modulated positional information, that is,time axis information showing an absolute position on a disk, is writtenas an ATIP (Absolute Time in Pre-groove) signal.

The ATIP signal is written so that its frequency become 22.05 kHz±1 kHzwhen an optical disk rotates at a predetermined speed, for example, at astandard speed. One sector of the ATIP signal corresponds with one datasector (2352 bytes) of writing data. When the writing data is written,the writing is performed while synchronizing the sector of the ATIPsignal with the data sector of the writing data.

FIG. 1 shows the frame structure of an ATIP signal. One frame has 42bits including first 4-bit SYNC, 24-bit time axis information (minutes,seconds, frame numbers, each for 8 bits), and 14-bit CRC (CyclicRedundancy Code) as an error detecting code. A CD-RW writing and readingdevice performs rotational control of the disk, that is, the spindleservo based on the SYNC of the ATIP signal.

In such the writing and reading device, interference elements such asscratch, dirt and fingerprint on a recording surface, mechanicalcharacteristic fluctuation (eccentricity, eccentricity of center ofgravity, skew and wobbling), electric characteristic fluctuation(degraded S/N and reflectivity fluctuation), and vibration and shockfrom outside affect reading of the above ATIP signal. In particular, inrecent years, the data writing and reading speeds to and from an opticaldisk have been increased dramatically. The influence of the interferenceelements upon the reading of the ATIP signal has been enlarged more andmore. When a reading error of the ATIP signal occurs, the spindle servois unstable. Degradation of the reading characteristic (seek time andtransfer rate) and deterioration of the writing characteristic occur. Inthe worst case, there are problems of disabled writing and reading andoccurrence of a writing error.

DISCLOSURE OF THE INVENTION

The present invention has been contrived in the above circumstances andan object of the present invention is to provide an optical writingdevice, an optical reading device, a recording-medium-writing method anda recording-medium-reading method, which can suppress occurrence of areading error of time axis information from a wobble so as to preventdisabled reading of information from an optical recording medium andoccurrence of a writing error.

An optical writing device according to the present invention has: wobblesignal generation means for generating a wobble signal from an electricsignal outputted from an optical pickup; evaluation means for evaluatingaccuracy of the wobble signal generated by the wobble signal generationmeans; and control means for allowing control, in performing writing toan optical disk, for interrupting a writing operation when the accuracyof the wobble signal evaluated by the evaluation means is deviated froma predetermined range. In addition, it has jitter measurement means formeasuring a jitter amount of the wobble signal. The evaluation meansevaluates the accuracy of the wobble signal at least based on the jitteramount of the wobble signal measured by the jitter measurement means.Further, an error detecting code is added to the wobble signal. Decodingmeans performs error detection with the error detecting code at decodingtime axis information generated from the wobble signal, and theevaluation means evaluates the accuracy of the wobble signal at leastbased on the error rate of the error detection. In addition, asynchronization signal for frame synchronization with writing data isadded to the wobble signal. Phase error measurement means for measuringa phase error between the synchronization signal and a synchronizationsignal of the writing data is provided, and the evaluation meansevaluates the accuracy of the wobble signal at least based on the phaseerror measured by the phase error measurement means. In addition, thecontrol means performs control, in performing writing, for interruptingthe writing operation, decelerating a writing speed, and restarting thewriting operation, when deciding that the accuracy of the wobble signalevaluated by the evaluation means is lower than a lower limit of thepredetermined range, and performs control for interrupting the writingoperation, accelerating the writing speed, and restarting the writingoperation, when deciding that the accuracy of the wobble signal ishigher than an upper limit of the predetermined accuracy range.

In addition, an optical reading device according to the presentinvention has: wobble signal generation means for generating a wobblesignal from an electric signal outputted from an optical pickup;evaluation means for evaluating accuracy of the wobble signal generatedby the wobble signal generation means; and control means for changing areading speed set under a CLV or CAV condition, in performing readingfrom an optical disk, when the accuracy of the wobble signal evaluatedby the evaluation means is deviated from a predetermined accuracy range.In addition, it has jitter measurement means for measuring a jitteramount of the wobble signal. The evaluation means evaluates the accuracyof the wobble signal at least based on the jitter amount of the wobblesignal measured by the jitter measurement means. In addition, an errordetecting code is added to the wobble signal. The decoding meansperforms error detection with the error detecting code at decoding timeaxis information generated from the wobble signal, and the evaluationmeans evaluates the accuracy of the wobble signal at least based on theerror rate of the error detection. Further, a synchronization signal forframe synchronization with writing data is added to the wobble signal.Phase error measurement means for measuring a phase error between thesynchronization signal and a synchronization signal of the writing datais provided. The evaluation means evaluates the accuracy of the wobblesignal at least based on the phase error measured by the phase errormeasurement means.

In addition, a recording-medium-writing method according to the presentinvention has the steps of: generating a wobble signal from an electricsignal from an optical pickup; evaluating accuracy of the wobble signal;and interrupting a writing operation to a recording medium when theevaluated accuracy of the wobble signal is deviated from a predeterminedrange.

Further, a recording-medium-reading method according to the presentinvention has the steps of: generating a wobble signal from an electricsignal outputted from an optical pickup; evaluating accuracy of thewobble signal; and changing a reading speed set under a CLV or CAVcondition when the evaluated accuracy of the wobble signal is deviatedfrom a predetermined accuracy range.

In the present invention, the accuracy of the wobble signal is evaluatedbased on the jitter amount of the wobble signal, the error detectedresult of the error detecting code added to the wobble signal, or thephase error between the synchronization signal added to the wobblesignal and the synchronization signal of the writing data When theevaluated result is deviated from the predetermined range, the writingoperation is interrupted at writing and then it restarts after thewriting speed has been changed. In addition, at reading, the readingspeed set under the CLV or CAV condition is changed. Changing thewriting and reading speeds allows the reading accuracy of the wobblesignal to be increased, thereby preventing disabled reading ofinformation from the optical recording medium and the occurrence of awriting error.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a frame structure of an ATIP signal;

FIG. 2 is a block diagram showing a configuration of an optical writingdevice according to an embodiment of the present invention;

FIG. 3 is a diagram showing a control flow in the optical writing deviceof FIG. 1;

FIGS. 4A to 4D are waveform charts each showing a wobble signal, an ATIPeye pattern generated therefrom, an FMDT signal and an FMCK signal; and

FIG. 5 is a diagram showing the relation between the synchronizationsignal of an ATIP and the frame synchronization signal of writing data.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described more in detailwith reference to the drawings. FIG. 2 shows a configuration of anoptical writing device for performing writing and/or reading ofinformation using an optical recording medium.

An optical writing device 1 is a device for performing writing andreading of information to/from a disk-like medium 100 such as a CD-RW.The medium 100 is fitted in a spindle motor 2 to be rotatively operated.The spindle motor 2 spins according to a driving of a spindle driver 3under the control of a system control part 11.

An optical pickup 4 has a semiconductor laser 5 for emitting an opticalbeam, a collimator lens 22 for converting the optical beam emitted fromthe semiconductor laser 5 to parallel light, a beam splitter 6 forbranching an optical path of the optical beam, an objective lens 7 forfocusing the light passing through the beam splitter 6 to irradiate itonto the medium 100, a focusing lens 23 for focusing return lightreflected by the medium 100 and reflected by the beam splitter 6, and anoptical detector 24 for receiving the return light focused by thefocusing lens 23 to convert it to an electric signal.

A laser driver 8 controls the semiconductor laser 5 of the opticalpickup 4 to make the output power thereof an optimal power for writing,reading, and erasing, respectively, under the control of the systemcontrol part 11.

The objective lens 7 of the optical pickup 4 is movably supported by abiaxial actuator, not shown, in the two-axle directions, namely, in aradial direction of the medium 100 fitted in the spindle motor 2 and ina direction that it is close to and apart from a recording surface ofthe medium 100. A servo control part 10 controls the biaxial actuator tomovably operate the objective lens 7 in the two-axle directions, therebyperforming a focus servo and a tracking servo in the optical pickup 4.

In addition, the optical pickup 4 is movably operated in a radialdirection of the medium 100 fitted in the spindle motor 2 so as toaccess a required recording track of the medium 100 by an accessmechanism (not shown) operated under the control of the system controlpart 11.

Output of the optical detector 24 of the optical pickup 4 is supplied toan RF signal processing part 12. The RF signal processing part 12generates an RF reading signal, a focus error signal, a tracking errorsignal and a wobble signal from a voltage signal supplied from theoptical detector 24. The RF reading signal generated by the RF signalprocessing part 12 is supplied to a digitization/clock generation part13.

The digitization/clock generation part 13 performs digitizationprocessing on the RF reading signal supplied from the RF signalprocessing part 12 to convert it to digital data and supplies thedigital data to a data processing part 14. The digitization/clockgeneration part 13 also generates a clock signal synchronized with thedigital data and supplies the generated clock signal together with thedigital data to the data processing part 14.

Under the control of the system control part 11, the data processingpart 14 EFM-demodulates the digital data supplied from thedigitization/clock generation part 13 and performs deinterleaveprocessing and error correction processing with CIRC (Cross InterleaveReed-Solomon Code). The data processing part 14 then performs descrambleprocessing and error correction processing with ECC (Error CorrectingCode) on the digital data.

The data subjected to the error correction processing in the dataprocessing part 14 is stored in a buffer memory 15 such as a DRAM andthen, it is supplied as reading data to a host computer via an interface16.

When the writing data is supplied via the interface 16 from the hostcomputer, the data processing part 14 sequentially reads out the writingdata from the buffer memory 15 such as a DRAM with the writing databeing temporarily stored into the buffer memory 15 and encodes it to apredetermined sector format to add the ECC for error correction to thewriting data. Further, the data processing part 14 performs CIRC encodeprocessing and EFM modulation processing on the writing data to generatea writing signal. Then, the writing signal is supplied to the laserdriver 8.

On the other hand, the focus error signal and the tracking error signalgenerated by the RF signal processing part 12 are supplied to the servocontrol part 10 and the wobble signal is supplied to an ATIP decoder 19,respectively.

The ATIP decoder 19 performs CRC check and decoding processing of thewobble signal supplied from the RF signal processing part 12 under thecontrol of the system control part 11 to generate an ATIP signal showingtime axis information. The ATIP signal generated by the ATIP decoder 19is supplied to the system control part 11 and is also supplied to ajitter measurement part 20 and a phase error measurement part 21. TheCRC error rate of the ATIP signal generated by the CRC check is alsosupplied to the system control part 11.

In addition, when performing the access operation of the optical pickup4, the system control part 11 controls the access mechanism, not shown,based on the ATIP signal to access the optical pickup 4 to the desiredrecording track.

The jitter measurement part 20 measures jitter of a signal (FMDT signal)obtained by the ATIP decoder 19 to supply the measured value thereof tothe system control part 11.

The phase error measurement part 21 measures a phase error (SYNC phaseerror) between the frame synchronization signal of the ATIP decoded bythe ATIP decoder 19 and the frame synchronization signal of the writingdata to supply the measured value thereof to the system control part 11.

The system control part 11 controls the operations of the entire opticalwriting device 1. The system control part 11 also controls theoperations of the respective parts of the optical writing device 1 usingan SRAM 17 as a work area based on a program for operation controlstored in a ROM 27.

To an EEPROM 28, ranges of set values of at least the respective CRCerror rate of the ATIP signal, FMDT jitter, and SNYC phase error areset.

The system control part 11 performs statistical processing such assimple average or moving average on the respective evaluated parametersof the CRC error rate detected by the ATIP decoder 19, the FMDT jitteramount obtained by the jitter measurement part 20, and the SNYC phaseerror obtained by the phase error measurement part 21 and compares theresults thereof with the ranges of set values. The system control part11 also performs control, for instance, during writing, for interruptingthe writing, for changing (decelerating or accelerating) the writingspeed, and for restarting the writing according to a predetermineddecision condition, for example, when any one of the three evaluatedparameters is deviated from the ranges of set values. The system controlpart 11 also performs control, during reading, for changing(decelerating or accelerating) the reading speed. Further, an upperlimit and a lower limit of the range changing the writing speed and thereading speed can be set and changed.

Next, the operations of writing information to the medium 100 by meansof the optical writing device 1 according to the present invention willbe described.

When writing information to the medium 100, the following processing isfirst performed in order to make the optical writing device 1 into a“ready” state that information can be written to the medium 100.

The medium 100 is fitted in the spindle motor 2. The spindle driver 3drives the spindle motor 2 under the control of the system control part11 to rotatively operate the medium 100. In addition, the laser driver 8drives the semiconductor laser 5 of the optical pickup 4 under thecontrol of the system control part 11 to allow the semiconductor laser 5to emit an optical beam of a predetermined power.

The optical beam emitted from the semiconductor laser 5 is converted toparallel light by the collimator lens 22, and then, it passes throughthe beam splitter 6 to reach the objective lens 7 focusing it. Theoptical beam is irradiated onto the medium 100 rotatively operated bythe spindle motor 2. The optical beam irradiated onto the medium 100 isreflected by the medium 100 to become return light including a wobblecomponent. The return light passes through the objective lens 7 to reachthe beam splitter 6 reflecting it, and then, is focused by the focusinglens 23 to enter the optical detector 24 to be received. The opticaldetector 24 performs photoelectric conversion and current-voltageconversion on the received return light to generate a voltage signalcorresponding to the return light. The voltage signal generated by theoptical detector 24 is supplied to the RF signal processing part 12.

The RF signal processing part 12 generates a wobble signal based on thevoltage signal supplied from the optical detector 24 and supplies it tothe ATIP decoder 19. The ATIP decoder 19 performs the CRC check anddecoding processing of the wobble signal under the control of the systemcontrol part 11 to generate an ATIP signal showing SYNC and time axisinformation for supplying it to the system control part 11.

The system control part 11 controls the driving of the spindle driver 3based on the ATIP signal so that the medium 100 fitted in the spindlemotor 2 can be rotatively operated at a speed set, for example, under aCLV or CAV condition.

According to the above series of processing, the optical writing device1 is brought into the “ready” state that a writing operation ofinformation can be performed on the medium 100.

Thereafter, when the data processing part 14 receives the writing datafrom the host computer, the data processing part 14 encodes the writingdata to a predetermined sector format and then, performs processing foradding the ECC for error correction, CIRC encode processing and EFMmodulation processing to generate a writing signal. Then, the dataprocessing part 14 supplies the writing signal with the laser driver 8.

The laser driver 8 drives the semiconductor laser 5 of the opticalpickup 4 according to the writing signal supplied from the dataprocessing part 14 under the control of the system control part 11.Thus, the semiconductor laser 5 emits an optical beam of a writing powermodulated according to the writing data.

The optical beam emitted from the semiconductor laser 5 is converted tothe parallel light by the collimator lens 22, and then, passes throughthe beam splitter 6 to be focused by the objective lens 7, thereby beingirradiated onto the medium 100 rotatively operated by the spindle motor2. The light beam irradiated by the medium 100 is reflected by themedium 100 to become return light including a wobble component. Thereturn light passes through the objective lens 7 to be reflected by thebeam splitter 6, and then, is focused by the focusing lens 23 to enterthe optical detector 24 to be received.

The optical detector 24 performs photoelectric conversion andcurrent-voltage conversion on the received return light to generate avoltage signal corresponding to the return light. Then, the voltagesignal generated by the optical detector 24 is supplied to the RF signalprocessing part 12.

The RF signal processing part 12 generates a wobble signal based on thevoltage signal supplied from the optical detector 24 and supplies it tothe ATIP decoder 19. The ATIP decoder 19 performs the CRC check anddecoding processing of the wobble signal under the control of the systemcontrol part 11 to generate an ATIP signal showing SYNC and time axisinformation for supplying it to the system control part 11. The systemcontrol part 11 performs control of the access mechanism, not shown, andthe spindle servo based on the ATIP signal.

Next, the operation of reading information from the medium 100 by meansof the optical writing device 1 according to the present invention willbe described.

When a reading command is supplied from the host computer via theinterface 16 to the system control part 11, the system control part 11controls the operation of the access mechanism, not shown, to travel theoptical pickup 4 in the radial direction of the medium 100 fitted in thespindle motor 2 so that the optical pickup 4 can be accessed to arequired recording track of the medium 100. In addition, the systemcontrol part 11 controls the operation of the laser driver 8 to drivethe semiconductor laser 5 of the optical pickup 4 for emitting anoptical beam with a reading power from the semiconductor laser 5.

The optical beam for reading emitted from the semiconductor laser 5 isconverted to the parallel light by the collimator lens 22, and then,passes through the beam splitter 6 to be focused by the objective lens7. Then, the optical beam for reading focused by the objective lens 7 isirradiated onto the medium 100 rotatively operated by the spindle motor2. An optical spot is formed along a pit array formed on the medium 100.

The optical beam for reading irradiated onto the medium 100 is reflectedby the medium 100 to become return light including a signal componentwritten as the pit array to the medium 100. The return light passesthrough the objective lens 7 to be reflected by the beam splitter 6, andthen, is focused by the focusing lens 23 to enter the optical detector24 to be received.

The optical detector 24 performs photoelectric conversion and currentvoltage conversion on the received return light to generate a voltagesignal corresponding to the return light. Then, the voltage signalgenerated by the optical detector 24 is supplied to the RF signalprocessing part 12.

The RF signal processing part 12 generates an RF reading signal, a focuserror signal, a tracking error signal and a wobble signal based on thevoltage signal supplied from the optical detector 24. The focus errorsignal and the tracking error signal generated by the RF signalprocessing part 12 are supplied to the servo control part 10. The servocontrol part 10 drives the biaxial actuator, not shown, based on thefocus error signal and the tracking error signal under the control ofthe system control part 11 and performs focusing servo and trackingservo in the optical pickup 4.

In addition, the wobble signal generated in the RF signal processingpart 12 is supplied to the ATIP decoder 19. The ATIP decoder 19 performsthe CRC check and decoding processing of the wobble signal under thecontrol of the system control part 11 to generate an ATIP signal showingSYNC and time axis information. The ATIP signal is supplied to thesystem control part 11. The system control part 11 performs control ofthe access mechanism, not shown, and the spindle servo based on the ATIPsignal.

In addition, the RF reading signal generated by the RF signal processingpart 12 is supplied to the digitization/clock generation part 13 wheredigitization processing is performed for conversion to the digital dataThen, the digital data is supplied to the data processing part 14.

The digital data supplied to the data processing part 14 is subject tothe EFM-demodulation processing, deinterleave processing, errorcorrection processing with CIRC and the like in the data processing part14. Further, the digital data is subject to the descramble processingand error correction processing with ECC to be stored into the buffermemory 15 such as a RAM, and then, is supplied as reading data via theinterface 16 to the host computer. This allows the information writtento the medium 100 to be read.

Next, in the writing and reading operations of information to/from themedium 100, an operation in which the accuracy of the wobble signal isevaluated and the operations of the optical writing device 1 arecontrolled according to the evaluated result will be described. FIG. 3shows a flowchart of this control.

When the routine is advanced from step 201 where a disk is inserted tostep 202, it is determined which any one operation of a writingoperation and a reading operation should be done in this step 202. Here,at the writing operation, the routine is advanced to step 203, and atthe reading operation, the routine is advanced to step 214.

In the step 203, measurement of parameters is carried out and anevaluation is then performed using the measured parameters. In otherwords, to evaluate the accuracy of the wobble signal, the system controlpart 11 performs statistical processing such as simple average or movingaverage of the respective evaluated parameters of the CRC error ratedetected by the ATIP decoder 19, the FMDT jitter amount obtained by thejitter measurement part 20, and the SNYC phase error obtained by thephase error measurement part 21. Subsequently, the system control part11 compares the respective statistical results thus obtained of the CRCerror rate of the ATIP signal, the FMDT jitter amount and the SYNC phaseerror with the respective ranges of set values stored into the EEPROM28.

FIGS. 4A to 4D show signals generated from the wobble signal. The wobblesignal shown in FIG. 4A is decoded, that is, the wobble signal issubject to FM-demodulation, thereby obtaining an ATIP signal shown inFIG. 4B. The ATIP signal is digitized, thereby obtaining an FMDT signalshown in FIG. 4C, and then, an FMCK signal shown in FIG. 4D is extractedas a clock by looping the FMDT signal in a PLL. The FMCK signal is usedin the spindle motor. The FMDT signal is also buffeted by the FMCKsignal, thereby obtaining the ATIP signal. The FMDT jitter is deviationof the FMCK signal and the FMDT signal on a time axis, which is Bi-Phasemodulated and has three kinds of pulse widths of 1T to 3T. Here, in thejitter measurement, all Ts of 1T to 3T may be measured. For example,only 1T may be simply measured.

FIG. 5 shows the relation between ATIP-SYNC signal as a synchronizationsignal of the ATIP and FRAME-SYNC signal as a frame synchronizationsignal of the writing data. 75 frames exist in one second in relation toeach of the frame of the ATIP signal and one frame (2352 bytes) of thewriting data. When the writing data is written, the writing is performedwhile synchronizing the frame of the ATIP signal with the frame of thewriting data. In other words, the spindle servo is performed with thephase error of the synchronization signal of the ATIP and the framesynchronization signal of the writing data being made zero. In the C-DRand C-DRW standards, the phase error is always satisfied in any locationon the medium within 0±2 EFM Frame (136 μsec at a standard speed). Thephase error measurement part 21 measures the phase error for supplyingit to the system control part 11. From this, the system control part 11performs the spindle servo based on the measured result of the phaseerror and performs statistical processing such as simple average ormoving average of the measured value of the phase error.

The system control part 11 decides whether the writing and readingspeeds are changed or not according to a predetermined decisioncondition based on the evaluated results of the above three evaluatedparameters.

In the decision condition, the following various modifications can bemade: {circle around (1)} the case that any one of the three evaluatedparameters is deviated from the set value range, {circle around (2)} thecase that two of the three evaluated parameters are deviated from theset value ranges, and {circle around (3)} the case that all of the threeevaluated parameters are deviated from the set value ranges.

In step 204, it is determined whether a speed change condition issatisfied or not. Here, when deciding in the above step 203 that thewriting and reading speeds are changed, the routine is advanced to step205, and when it has not decided that the writing and reading speeds arechanged, the routine is advanced to step 206.

In the step 205, the writing and reading speeds are changed. In otherwords, when the evaluated parameter exceeds the range of set values, thewriting speed is decelerated and the decelerated writing speed is set asan initial value. Reversely, when the evaluated parameter does not reachthe range of set values, the writing speed is accelerated and theaccelerated writing speed is set as an initial value. In this manner,the processing of the steps 201 to 205 is performed so that the opticalwriting device 1 may become the state before starting writing, that is,the “ready” state that writing of information can be performed to themedium 100.

In the step 206, the writing is started at a set speed and the routineis advanced to step 207. In the step 207, it is determined whether awriting termination address is provided or not. Here, when the writingtermination address is provided, the writing is terminated. When thewriting termination address is not provided, the routine is advanced tostep 208.

In the step 208, the same processing as that of the step 203 isperformed during the writing operation and the routine is advanced tostep 209.

In the step 209, it is determined whether the speed change condition issatisfied or not. Here, when it has been determined, in the step 208,that the writing and reading speeds are changed, the routine is advancedto step 210. When it has not been decided that the writing and readingspeeds are changed, the routine is returned to step the 207.

In the step 210, the writing is interrupted or the writing isinterrupted at the point at which the writing can be interrupted and theroutine is advanced to step 211. In the step 211, it is determinedwhether a speed set range is exceeded or not. The speed set range showsthe upper limit and the lower limit of the range for changing thewriting speed, which are set previously, based on, for example, theabove-described evaluated parameters, the characteristic of the medium100 of whether coping with a high-speed operation is enabled or not, andthe eccentric amount of the medium 100. Here, when the changed speedexceeds the speed set range, the writing operation is terminated. Inaddition, when it does not exceed the speed set range, the routine isadvanced to step 212.

In the step 212, the writing speed is changed and the routine is thenadvanced to step 213. In the step 213, the writing is restarted at thechanged speed and the routine is returned to the step 207. In otherwords, when the evaluated parameter exceeds the range of set values, thewriting is interrupted to decelerate the writing speed for restartingthe writing. Reversely, when the evaluated parameter does not reach therange of set values, the writing is interrupted to accelerate thewriting speed for restarting the writing.

Here, the point at which the writing can be interrupted refers to, forexample, a writing termination point of the data of one packet in thecase of writing by a packet write method. An optical writing devicehaving a function of interrupting the writing and restarting the writingfrom the position immediately after the interrupting, can interrupt thewriting immediately after establishing the writing speed changecondition.

As a timing for restarting the writing, for example, there exists atiming at which deceleration of the writing speed is completed, a timingat which more than a fixed amount of writing data is stored into thebuffer 15, or a timing at which a fixed time elapses from stopping.

After changing the writing speed, when the writing speed changecondition is established again, the writing is interrupted again and thewriting speed is then decelerated or accelerated to allow the writing torestart. Thereafter, changing of the writing speed is repeated, therebycompleting the writing.

In addition, in reading the information from the medium 100, the routineis advanced from the step 202 to the step 214. In the step 214, as inthe step 203, measurement of parameters and evaluation are performedusing the measured parameters.

In step 215, it is determined whether a speed change condition issatisfied or not. Here, when the speed change condition is notsatisfied, the routine is returned to the step 214. When the speedchange condition is satisfied, the routine is advanced to step 216.

In the step 216, it is determined whether a speed set range is exceededor not. The speed set range shows the upper limit and the lower limit ofthe range for changing the reading speed, which are set previously as inthe case of the speed set range of the above-described writing speed.Here, when the changed speed exceeds the speed set range, the routine isreturned to the step 214. In addition, when it does not exceed the speedset range, the routine is advanced to step 217.

In the step 217, the reading speed set under the CLV or CAV condition ischanged. In other words, when the evaluated parameter exceeds the rangeof set values, the reading speed is decelerated while continuing thereading. Reversely, when the evaluated parameter does not reach therange of set values, the reading speed is accelerated. Thereafter,change of the reading speed is repeated for completing the reading.

As described above, according to the optical writing device 1 embodyingthe present invention, in order to evaluate the accuracy of the wobblesignal, the evaluated parameters such as the CRC error rate of the ATIPsignal, the FMDT jitter amount, and the phase error of the ATIPsynchronization signal and the frame synchronization signal of thewriting data are evaluated based on the ranges of set values. When theevaluated parameter is deviated from the ranges of set values, thewriting and reading speeds are changed so that the reading accuracy ofthe wobble signal can be increased, thereby preventing disabled readingof information from the medium 100 and occurrence of a writing error.

It should be noted that the present invention is not limited to only theabove embodiment, and needless to say, various modifications can beadded within the scope without departing from the purpose of the presentinvention.

The optical writing device targeted by the present invention can beapplied, not only to an optical writing medium device using a CD-RWdescribed in the above embodiment as an optical recording medium, butalso to an optical writing device which uses an optical disk in whichwobble including time axis information is provided along a recordingtrack such as a CD-R, DVD-R, DVD-RW, DVD+R, DVD+RW and DVD-RAM and anoptical recording medium such as an optical card other than the disk.

As described above in detail, according to the optical writing device,the optical reading device, the recording-medium-writing method and therecording-medium-reading method of the present invention, reading ofaddress information included in wobble is stable and information can bestably written and read to/from an optical recording medium.

INDUSTRIAL APPLICABILITY

The present invention is useful when writing and reading informationto/from an optical recording medium and is preferred for suppressingoccurrence of a reading error of time axis information from wobble tostably write and read information.

1. An optical writing device comprising: a wobble signal generationmechanism configured to generate a wobble signal from an electric signaloutputted from an optical pickup; an evaluation mechanism configured toevaluate an accuracy of the wobble signal generated by said wobblesignal generation mechanism; a controller configured to interrupt, inperforming writing to an optical disk, a writing operation when theaccuracy of the wobble signal evaluated by said evaluation mechanism isdeviated from a predetermined range; and a jitter measurement mechanismconfigured to measure a jitter amount of the wobble signal, wherein saidevaluation mechanism evaluates the accuracy of the wobble signal atleast based on the jitter amount of the wobble signal measured by saidjitter measurement mechanism.
 2. The optical writing device according toclaim 1, wherein an error detecting code is added to the wobble signaland a decoder means performs error detection with the error detectingcode at decoding time axis information generated from the wobble signal;and wherein said evaluation mechanism evaluates the accuracy of thewobble signal at least based on the error rate of the error detection.3. The optical writing device according to claim 1, wherein asynchronization signal for frame synchronization with writing data isadded to the wobble signal, and phase error measurement mechanismmeasures a phase error between the synchronization signal and asynchronization signal of the writing data is further provided; andwherein said evaluation mechanism evaluates the accuracy of the wobblesignal at least based on the phase error measured by said phase errormeasurement mechanism.
 4. An optical reading device comprising: a wobblesignal generation mechanism configured to generate a wobble signal froman electric signal outputted from an optical pickup; an evaluationmechanism configured to evaluate an evaluating accuracy of the wobblesignal generated by said wobble signal generation mechanism; acontroller configured to change a reading speed set under any one ofconstant linear velocity (CLV) and constant angular velocity (CAV)conditions, in performing reading from an optical disk, when theaccuracy of the wobble signal evaluated by said evaluation mechanism isdeviated from a predetermined range; and a jitter measurement mechanismconfigured to measure a jitter amount of the wobble signal, wherein saidevaluation mechanism evaluates the accuracy of the wobble signal atleast based on the jitter amount of the wobble signal measured by saidjitter measurement mechanism.
 5. The optical reading device according toclaim 4, wherein an error detecting code is added to the wobble signal;wherein a decoding mechanism performs error detection with the errordetecting code at decoding time axis information generated from thewobble signal; and wherein said evaluation mechanism evaluates theaccuracy of the wobble signal at least based on the error rate of theerror detection.
 6. The optical reading device according to claim 4,wherein a synchronization signal for frame synchronization with writingdata is added to the wobble signal and a phase error measurementmechanism measures a phase error between the synchronization signal anda synchronization signal of the writing data is further provided; andwherein said evaluation mechanism evaluates the accuracy of the wobblesignal at least based on the phase error measured by said phase errormeasurement mechanism.